Add correct String/ChannelBuffer injections

[franklinhu]

The String and ChannelBuffer injections provided in storehaus-mysql are flipped (there's always a mapping to MySqlValue but not always back). Added injections in the right direction and deprecated the existing ones.

• Add String2MySqlValueInjection and ChannelBuffer2MySqlValueInjection
• Deprecate MySqlStringInjection and MySqlCbInjection

[johnynek]

Yes, it does look like the original ones are a bit ill-formed. Can you add some tests here? The IsInjection property is pretty easy to use as long as you have the Gen/Arbitrary for the types in question.

[franklinhu]

It looks like IsInjection is only accessible in bijection-core?https://github.com/twitter/bijection/blob/23b7978fd8a4948ad294aa44fda35db5747950bd/bijection-core/src/test/scala/com/twitter/bijection/BaseProperties.scala#L66-L68

It also seems like we could remove the storehaus MySqlValue wrapper over the Finagle types since bijection-finagle-mysql exists now?

[johnynek]

sadly those BaseProperties are not exported. You'll have to do something like:

forAll { (i: Int) =>
  injection.invert(injection(i)) == Success(i)
}

is good enough.

About bijection-finagle-mysql: yes we should remove the repeated code here (once the tests are passing on that and we have a new published version). For now let's make an issue with the correct links.

[franklinhu]

Added the tests, and ended up discovering a bug in how ChannelBuffers are converted to MySQL types.

[johnynek]

Thanks for this! Looks good.